A printing plate useful for printing newspapers, magazines and other printed material, and a process for making such printing plate.
Printing plates for the high-speed printing of newspapers and magazines are well known. Reference may be had, e.g., to U.S. Pat. No. 6,076,474 (computer to plate printing technique), U.S. Pat. Nos. 5,976,763, 5,962,111 (liquid photopolymerizable resin cured by exposure to actinic radiation), U.S. Pat. No. 5,795,689 (method of making a printing plate for newspaper printing), U.S. Pat. No. 5,223,041 (processing of printing plates to remove unreacted photopolymer), U.S. Pat. No. 5,081,033 (developer composition for newspaper plates), U.S. Pat. Nos. 4,540,649, 4,407,862, 4,289,071, 4,283,481 (phosphine-activated photosensitive compositions), 4,263,392, 4,248,959, 4,234,676, 4,233,391, 4,115,123, 4,115,119, 4,101,324, 4,072,529, 4,044,385, 4,017,183, and the like. The entire disclosure of each of these United States patents is hereby incorporated by reference into this specification.
The printing plates used for newspaper and magazine printing often have aluminum, mylar (polyester), or steel substrates. See, e.g., U.S. Pat. Nos. 6,145,565, 6,076,464, 6,066,424, 6,064,465, 5,967,048, 5,894,319, 5,714,289, 5,712,077, 5,961,104, 5,670,283, 5,637,428, 5,626,996, 5,620,822, 5,589,307, 5,569,573, 5,501,929, 5,432,046, 5,395,721, 5,391,445, 5,282,952, 5,223,041, 5,219,687, 5,208,126, 5,061,598, 4,731,317, 4,645,730, 4,501,810, 4,414,315, and the like. The entire disclosure of each of these United States patents is hereby incorporated by reference into this specification.
One of the problems with prior art printing plates is halftone dot gain associated with the exposure of the plate and halftone dot size loss during the printing process. As is known to those skilled in the art, halftone dot gain is made up of both physical and optical effects, wherein a physical gain is an actual physical change in the size of the dot and optical gain is an optical enhancement due to internal reflections within the composite surrounding the halftone dot. Loss in halftone dot size during the printing process is caused by ink chemistry and physical abrasion of the plate by the printing process. Slight changes in the halftone dot size can cause can cause significant changes in visual color perception. Reference may be had, e.g., to U.S. Pat. Nos. 6,181,439, 6,176,427, 6,098,738, 6,007,967, 5,903,712, 5,888,367, 5,875,288, 5,813,333, 5,763,122, 5,726,772, 5,708,518, 5,659,385, 5,493,327, 5,493,321, 5,382,282, 5,235,432, 5,173,113, 5,146,548, 5,120,624, 4,208,963, 4,004,923, and the like. The entire disclosure of each of these United States patents is hereby incorporated by reference into this specification.
It is an object of this invention to provide a process for preparing a durable printing plate which has improved halftone dot gain and halftone dot size loss properties.
In accordance with this invention, there is provided a process for preparing a printing plate comprising the step irradiating a developed plate with deep ultraviolet light at a wavelength of from about 170 to about 290 nanometers.